I played some Ancients and Memoir '44 and then made up a Franco-Prussian War modification for Commands and Colors Napoleonics.
Here are some shots of a made up scenario...
A great game with plenty of exciting action.
The modifications I made to the rules were few.
French infantry were given a 3 hex range, while the Prussian infantry only had a 2 hex range but were given an extra die in melee.
The French artillery was kept the same as the Napoleonic rules but the Prussian guns had ranges values of 332211 as in Memoir '44.
I could have fiddled about with other modifications but these worked fine for me, the simpler the better.